Pro Bono work and Public Relations

From time to time I reflect on the career path that I've chosen for myself and wonder what good it will bring to humanity. Seriously. People choose to become doctors, nurses, psychologists, scientists, lawyers, judges, and all these careers help individuals in some way. Advertising and PR on the other hand can sometimes appear to be all about helping a company make a profit. Sometimes I see it that way too...
But it's not my fault that my talents lie in the ability to craft persuasive messages, in understanding pathos, logos and ethos and their effects, is it? I mean, not everyone can be a doctor!
As a soon to be college graduate, the simple solution would be to seek out companies that I view as standing for those things I believe in, those companies that in someway help people who need help. But of course this is easier said than done in an economy where beggars can't be choosers.
All PR agencies, in my humble opinion, should try to do pro bono work for small organizations on an ongoing basis. I know...there are only 8 hours in a working day (supposedly) and staff should focus on clients, but as a profession sometimes seen as the bad guys/the spin doctors...PR should do a little repuation mangement of its own sometimes.